Giant electrode

ABSTRACT

A giant electrode of graphite for high-output operation of electric arc furnaces in which the electrode is provided with an electric arc stabilizing wick.

United States Patent Zollner et al. 1 Feb. 22, 1972 [54] GIANT ELECTRODE[72] Inventors: Dieter Zollner, Erlangen; Bernhard [56] ReferencesRe|chelt, Numberg-Laufamholz, both of UNITED STATES PATENTS G many859,292 7/1907 Harden ..l3/18 X 1 Asslsnw Conrad! Numbers, Germany3,120,453 2/1964 Fitzer et a]. ..13/18 x [22] "3" PrimaryExaminer-Remand A. Gilheany [21] Appl. No.: 45,426 Assistant ExaminerR.N. Envall, Jr.

, Attorney-Walter Becker 30 v Foreign Application Priority Data '[57]ABSTMCT June 13, Germany ..P A g electtode of for highoutput operationof electric arc furnaces in which the electrode is provided with [52]US. CL ..13/ 18 an electric arc stabilizing wick [51] Int. Cl. 05b 7/06[58] Field of Search ..l3/l8; 314/60; 313/354 2Clalms,2Drawlng FiguresThe present invention relates to a giant electrode of graphite forelectric arc furnaces.

The technical requirement to convey extremely high electric power inconnection with the melting operation of electric arc furnaces to thematerial to be melted and heated in the hearth has lead to numerousimprovements in graphite electrodes. However, with regard to the extentto which solid graphite electrodes can be subjected to current loads hasprincipally reached a limit. In order, in spite of this limit, still tobe able to transmit greater power, resort has been taken to increasingthe voltage. The increase in the voltage while retaining the current,however, entails other difficulties in the electric arc furnaceoperation. Thus, the electric are which, in view of the higher voltagesis longer, causes an unsteady burning behavior and, in view of thisinstability, brings about a considerable turbulence in the surface ofthe melt. These turbulences bring about that steel and slag particlesare thrown against the lateral hearth lining and thus result in anintolerable extreme wear of the furnace lining.

Therefore, it became imperative to stabilize the electric are as far aspossible. To this end, hollow electrodes of graphite have been used. Inview of the tendency of the foot point of the electric arc to burn inthe interior of the central bores, a stabilization was realized whichcould be improved furtherby the supply of gases, such as argon, forstabilizing the electric arc and by stabilizing additions at the wallsof the electrode.

While these methods bring about considerable advantages, very frequentlythe graphite consumption figures were considerably higher than expectedor the operating costs with gasstabilized hollow electrodes became toohigh.

It is, therefore, an object of the present invention to provide a giantelectrode which will overcome the above-mentioned drawbacks.

This object and other objects and advantages of'the invention willappear more clearly from the following specification in connection withthe accompanying drawing, in which:

FIG. 1 is a section through an electrode according to the invention,while FIG. 2 is a top view of the electrode of FIG. 1.

The present invention, which concerns a giant electrode of graphite formaximum output operation of electric arc furnaces, is characterized inthat it comprises an electric arc stabilizing wick.

Wick electrodes with small diameter are principally known for use inconnection with movie projection lamps and for illuminating purposes. Insuch an instance, synthetic carbon products are involved of a diameterof up to 20 mm. and a length of approximately 50 cm.

The present invention is concerned with the application of thisprinciple of increasing the power of electrodes to giant electrodes forthe electric arc furnace. The advantage of this new electrode resultsfrom a combination of individual effects. In this connection there areto be mentioned:

We claim:

1. A giant electrode of graphite for maximum power operation of electriclight arc furnaces, which comprises a graphite body having an axialcentral bore of small diameter therethrough compared to total electrodecross section, and a thin wick arranged centrally in said bore, saidthin wick specifically assuring stabilization of electric light arefurnace operation and simultaneously reducing graphite consumption.

2. An electrodeof electric light are furnaces according to claim 1, inwhich the mass of the thin wick contains a compound selected from thegroup consisting of n TiC and TiN in which n is selected from one tofour for stabilization at higher current load demand during maximumpower operation of electric light are furnaces.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECHON Patent No. 3, 4Dated February 22, 1972 t Inventor) Dieter Zollner, a a1 It is certifiedthat error appears in the above-ide'ntified patent and that said LettersPatent are hereby corrected as shown below:

Column 2 after line 20, insert the following:

1. m elsamc current loadability. m, while an graphite electrode ofdiameter can he st lbj'e Cted to an electric current load of SO kA,which by impregnatioh uithmar and pitch prior to the graphiti zingoperation can increased to nearly kA, it is possible to sfibject a 20electrode of graphite according to the ihvention also fi m impregnationto load of kit. The drawbacks of A impregnated electrodes, such asincreased tear danger in view of thehigh density and accordingly'reduced chemo-shock 'v resistance,- are completely-absent v vith wickelectrode a according to the invention.. Similar to' the 110110;electrode, the safety of operation is even considerably increased btacau se in'view-of the-porous:-wickl-structure;flas compared-to thesolid t'lectrode, the graphite electrode has also expansion possibil-it:

' with regard to the wick."

FORM PO-O (10-69) USCOMWDC 503764; a u.s. aovznunrm' manna omc! mso-ue-au,

Patent No. 3,6l .L;.,65) Page 2' 2.- with th-e hollow electrode, thestabil-izing affect is om the. size 0f the bore so that a relativelyhigh war -"w te Waste results from proming a sufficiently large me. Incontrast thereto, the wick electrode according to invention gets by wither small bores. Thus with an having a d'mter of 5 00 'm', in: instancjeaj bore of 1fiw -wi.ll suffice for pmdficifig stabilizing efifeiit.

3. me uick'electrode-ancosding theinwentiongenemtes a mlmly quiet 1yburning artwhich has almdist idealsine and thus veryl ong arcs :of

4. Finally, the cmtion -of zhem solid 'grapk xit e is" the am aom to thev the Int 1 thgwi k' s-.-

tin -electric a e the; 4

onto" the wick :doszlngi I 1y favorablere- Patent No. 3,6l. .l;,,65l4.Page 3 i .1 which as electric d, such as 1 r 141, The formation of TitTiN may be ob -zoxaldes'horethertitanium as well Em" i As will be: seenfrbw-the cirfliflge chewel'ec-tmfi g gia ph 'i t mew-ickg.-- The mass 6fm at Quayconsist of the referred. ta above,

It is, of course, up be zmderstooci that the present in ma is, by no,means, limited to the specific disclosure m forth above but alsoeomptises mq difications within KID taupe of the r claims.

' Signed and sealed this 26th day of February 19m.

(mm) Attest:

f C. MARSHALL DANN Commissioner of Patents EDWARD M.FLETCHER,JR.Attesting Officer

2. An electrode of electric light arc furnaces according to claim 1, inwhich the mass of the thin wick contains a compound selected from thegroup consisting of n TiC and TiN in which n is selected from one tofour for stabilization at higher current load demand during maximumpower operation of electric light arc furnaces.